chemical engineering process control and instrumentation Mcqs
151. Smoke density of the flue gas going out of the chimney is measured by a __________________?
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A. Thermal conductivity meter

B. Polarograph

C. Chromatograph

D. Photo electric cell
152. What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
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A. < 1

B. 1

C. None of these

D. > 1

153. Pressure of 0.0001 absolute psi can be measured by _____________ gauge?
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A. None of these

B. Thermocouple

C. Pirani

D. Mcleod
154. The temperature of tempering oil baths maintained at 400C during heat treatment of steel is measured by a/an _____________ thermocouple?
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A. Iron-constantan

B. Chromel-alumel

C. None of these

D. Platinum-platinum/rhodium

155. The deflection in diaphragm (which is used as pressure sensor in pneumatic and electronic instruments) is dependent on the metal thickness, its diameter D. and shape & number of corrugations. Its deflection is proportional to_______________?
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A. d2

B. d

C. d3

D. d4
156. According to Bode stability criterion, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is_________________?
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A. 90

B. 45

C. 180

D. 0

157. A simple pitot tube measures the___________________?
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A. Average velocity

B. Point velocity

C. Maximum velocity

D. Static pressure
158. Gas analysis is commonly done using the___________________?
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A. Mass spectrometer

B. Emission spectrometer

C. X-ray diffraction

D. Thermal conductivity cell
159. Which of following error integral is considered as the best criterion in controller settings ?
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A. None of these

B. ?0 ? |e| dt

C. ?0 ? e2 dt

D. ?0 ? |e2| dt

160. The transfer function of a second order system is _____________________?
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A. 1/(T2s2 + 2Ts + 1)

B. 1/(T2s2 + 2?T + 1)

C. 1/(T2s2 + 2?Ts + 1)

D. None of these

161. The second order system with the transfer function 4/(s2 + 2s + 4) has a damping ratio of ___________________?
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A. 2

B. 4

C. 1

D. 0.5
162. Instrumentation in a plant offers the advantage of_______________?
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A. Greater operation economy

B. Greater safety of operation

C. All A., B. and C.

D. Better quality of product

163. Emf developed by a thermocouple while measuring a temperature of 800C is about 31 mV. The type of thermocouple used is________________?
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A. Iron-constantan

B. None of these

C. Platinum-platinum + rhodium

D. Chromel-alumel
164. ____________ is the static characteristics of an instrument?
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A. Response

B. Drift

C. Tine lag

D. Dynamic error

165. Strain gage pressure transducers are used to measure _____________ pressures?
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A. Gage as well as vacuum

B. Absolute as well as differential

C. Both A. and B.

D. Neither A. nor B.

166. Strain gage uses an electrical conductor wire, which when elastically stretched increases in length and reduces in diameter. Both these dimensional changes result in ____________ in the electrical resistance of the wire ?
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A. Increase

B. Decrease

C. No change

D. Exponential decrease

167. Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the ________________?
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A. Mercury in glass thermometer

B. Iron-constantan thermocouple

C. Optical pyrometer

D. Alcohol filled thermometer

168. Emf generated in a thermocouple depends on the temperature ___________________?
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A. Difference between cold junction and atmospheric temperature

B. Of hot junction only

C. Of cold junction only

D. Difference between hot and cold junctions
169. Platinum resistance thermometer is the international standard for temperature measurement between __________________?
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A. Triple point of hydrogen and freezing point of antimony

B. 13.81K to 903.9K

C. Both A. and B.

D. Neither A. nor B.

170. Which of the following instruments is not used for measuring sub-zero (<0) temperatures ?
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A. Mercury in glass thermometer

B. Platinum resistance thermometer

C. Radiation pyrometer

D. Vapor pressure thermometer

171. A magnetic flowmeter is_________________?
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A. Capable of measuring the flow rate of slurries and electrolytes

B. Based on the principle of Faradays law

C. All A., B. and C.

D. Based on the linear relationship between the fluid flow rate and the induced voltage

172. Which of the following controllers has maximum offset ?
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A. P-I controller

B. P-D controller

C. P-controller

D. P-I-D controller

173. Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
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A. Radiation/infrared pyrometer

B. Mercury in glass thermometer

C. Filled system thermometer

D. Thermo electric pyrometer

174. The _____________ of a vapor pressure thermometer is a functioning element?
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A. Bulb

B. Pointer

C. None of these

D. Bourdon tube

175. Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( 0.1s)/(0.5s + 1) are known with a possible error of 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as________________?
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A. 12, 0.6, 0.12

B. 12, 0.4, 0.08

C. 8, 0.6, 0.08

D. 8, 0.6, 0.12

176. Feed forward controller accounts for the ______________ changes?
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A. Set point

B. Load

C. Both A. & B.

D. Neither A. nor B.

177. Thermistors are used in ____________ devices?
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A. Voltage measuring

B. Temperature measuring

C. Temperature compensating

D. Both B. & C.
178. Which of the following thermocouples is the most suitable for measuring a temperature of about 1600C in an oxidizing atmosphere ?
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A. Chromel-alumel

B. Copper-constantan

C. Iron-constantan

D. Platinum-platinum + rhodium
179. Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity ?
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A. O2

B. N2

C. CO2

D. CO

180. Temperature measurement by optical pyrometer is done above ____________ point, which is 1063C ?
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A. Nickel

B. Antimony

C. Silver

D. Gold
181. ______________ is undesirable in thermocouples used in industries ?
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A. Oxidation resistance

B. Linear relation of emf to temperature

C. Non-linear relation of emf to temperature

D. Corrosion resistance

182. Liquid discharge from a tank or reservoir cannot be measured by __________________?
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A. Orificemeter

B. Mouthpieces

C. Weirs

D. Notches

183. Which thermocouple can be used to measure a temperature of around 1400C ?
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A. Copper-constantan

B. Aluminium-Chromel

C. Platinum-platinum + rhodium

D. None of these

184. Emission spectroscopy is used for__________________?
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A. Solids and metal analysis

B. Determining water purity

C. Determination of CO2 in gases

D. NOx determination

185. In Bode plot, ? vs. ? is plotted on a/an ______________ graph paper?
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A. Triangular

B. Semi-log

C. Ordinary

D. log-log
186. Phase lag of the frequency response of a second order system to a sinusoidal forcing function______________?
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A. Approaches 180 asymptotically

B. Is 120

C. Is 30

D. Is 90 at the most

187. Reset rate is the another term used for ____________ time?
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A. Derivative

B. None of these

C. Dead

D. Integral
188. Flow rate of sludge is not measured by a/an_________________?
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A. Orificemeter

B. Open weir

C. Kennison nozzle

D. Both B. & C.
189. pH meter has ____________________?
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A. Three cells

B. Two cells

C. One cell

D. No cell

190. Which of the following thermocouples is capable of measuring a temperature of -50C ?
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A. Copper-constantan

B. Platinum-platinum + rhodium

C. Chromel-Alumel

D. Iron-constantan

191. Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit ?
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A. Thomson effect

B. Peltier effect

C. Seebeck effect

D. Joule heating effect

192. ____________ stability method uses open loop transfer function?
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A. Mikhailov

B. Ruth

C. Nyquist

D. None of these

193. The calibration data of a thermocouple with its cold junction at 0C are given below. The hot junction of the thermocouple is placed in a bath at 80C, while its cold junction is at 20C. What is the emf of thermocouple ?
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A. 2.46 mv

B. 3.26 mv

C. 0.80 mv

D. 2.43 mv

194. A manometer measures the _____________ pressure?
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A. Absolute

B. Atmospheric

C. None of these

D. Gauge
195. For measuring the temperature of a red hot furnace, which is the most suitable instrument ?
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A. Thermocouple

B. Optical pyrometer

C. Bimetallic thermometer

D. Platinum resistance thermometer

196. Bourdon gauges are used for measuring pressure (kg/cm2) ?
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A. < atmospheric

B. > 2 (gauge)

C. 10 (absolute)

197. Mercury thermometer is commonly used for low temperature measurement. The freezing point and boiling point of mercury are respectively _____________ C?
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A. 39 and 350

B. 79 and 395

C. 10 and 425

D. 51 and 439

198. Out of the following thermocouple wire insulating material, the highest temperature rating is for________________?
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A. Teflon

B. Fibre glass

C. Asbestos

D. Ceramic fibre
199. Zirconia probe is used for the measurement of___________________?
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A. Humidity of air

B. % O2 in flue gas

C. Speed of a submarine

D. % CO2 in flue gas

200. ______________ controller has the maximum stabilising time?
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A. PI

B. P

C. PD

D. PID